Frank e



I(Ne Medel.)

F. R. COLVIN.

TELEPHONE SYSTEM.

Ne. 511,589. Peteeted Dee. 26.1893.

. PIM.

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UNITED STAT-Es PATENT OFFICE.

FRANK R. coLvIN, or New YORK, N. Y.

TELEPHoNEwsYsTEM.

SPECIFICATION forming part of Letters Fatent No. 511,589, dated December 26, 1893.

Application filed June 26, 1893. Serial No. 478,803. (No model.)

To all whom t may concern,.-

Be it known that I, FRANK R. CoLvIN, a citizen of the United States, residing in the city, county, and State of New York, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

This invention relates to telephone systems and has for its object to permit telephonic intercommunication between a plurality of stations without the intermediation of a telephone exchange. rlhe systemis particularly applicable to what are known as house systems, where, as in a building or factory, it is important to establish intercommunication between a number of offices without incurring the expense of an exchange, with its expensive equipment and special operator, although it is also applicable to cases where there are a plurality of stations desiring mutual intercommunication distributed over a wider range of territory.

tIn carrying out my system I employ an independent wire for each station of the system and connect at each station, to the several wires except the wire lcorresponding to that station,a series of calling keys or spring-controlled circuit-closers which can only close the circuit to a particular station called while held in an abnormal position, and which, when the hand of the operator is removed, will spring into the normal position and open the circuit. The several anvils of these circuit-closers are provided with a common connection to one pole of an electric generator at each station, the other pole of which includes the station telephone normally short-circuited and connecting with ground ora common return wire for all the stations. A calling instrument is placed at each station connected to the individual wire of the station and the common return, and this branch preferably includes the a desk or table.

The several features of novelty of the invention will be more particularly hereinafter described and will .be definitely indicated in the claims appended to this specification.

In the accompanying drawings which illustrate the invention, Figure l is a diagram of a system embodying my invention, and Fig. 2 is a plan view of the circuit-closer.

The several individual wires 1, 2, 3, 4, of the system'may be carried throughout the entire system or may extend between such stations as require intercommunication. The system will be described as having all of these wires extending throughout the entire system, though it will be understood that in cases where the stations are separated a considerable distance if one or more subscribers do not need communication with allot the other subscribers only such individual wires as correspond to the stations with which communi-- tion. The wires may be arranged in the form ot' a cable for convenience of handling. Four such wires suitable for a system having four stations are shown at l, 2, 3, 4 in Fig. 1, and the several stations of the system are lettered A, B, C, D. At each station will be placed a series of circuit-closers suitably mounted on a portablestand, as indicated in Fig. 2,"as many in number as there are points to be communicated with, and opposite the circuitclosers will be arrangedfas shownv in Fig. 2, a series of name vplates upon whichv may be printed t-he names of the persons corresponding to the stations.

As there are four stations indicated in the system shown in Fig. l, three circuit-closers at each station will permit that station to establishtelephonic communication with any of the others. The circuit-closers are connected to the individual wires; for example, wire l corresponding to station A has at stations B, C and D a permanent connection with a circuit-closer; similarly, wire 2 corresponding to station B has permanent connections at Astations. A, C and D with circuit-closers at those points, and so on for the other individual wires. These circuit closers are normally cation is required need be carried to that stanection with one pole of thestation'battery,

as indicated at E, station A, the other pole of the battery leading to earth or to a common return wire through the station telephone which is normally short-circuited, but so arranged that when removed from its support the short-circuit will be broken. A coiivenientinode of eftectingthis resultconsists in providing the telephone with a metallic eye which is connected with one binding-post, which, when it rests upon a supporting hook electricallyconnected withthe other binding-post, establishes a short-circuit, but when the telephone is lifted off the eye this short-circuit is broken, and any current flowing by way of the telephonewill be forced to traverseitscoils. For example, the telephone terminals or cords t, t are'connected with the battery and common return; the hook h connects with the battery and terminal t', and the eye e connects with the common return and terminal t. The call-bell F is placed in the short-cir cuitF, 7L c, t. Froin the construction thus described it will be seen that Whenany station desires communication with any other, the circuit-closer corresponding to the station wantedis pressed and current will flow from the home battery through the circuit-closer to the individual Wire of tlie station wanted, thence through the call-bell of thatstation, by

Way of the short-circuit around its telephone to the ground wire or return, and back to the calling station through the short-circuit aroundits telephone to the other pole of its battery. The operators remove their telephones from the supports, thus opening the short-circuit and quieting the bells, and confimunication between the two stations may continue so long as the operator at the calling station holds down the circuit-closer.

Any suitable transmitting and receiving outfit may be employed; as shown a combined magneto transmitter and receiver is employed, the magnetism being generated by the calling battery. lVlien the conversation is ended the circuit-closer is released, and by reason of its being spring-controlled, opens the connections with the individual wire and restores the normal condition of aitairs. It: is of the utmost importance in a system of this character that the normal condition of alairs shall not by any possibility be capable of disturbance by reason of an oversight on the part of an operator; for example, if a reset-ting ofthe circuit-closer were necessary at the close of a conversation, the failure of the operator to reset it would upset the systeni, polarizing the battery, and until suoli condition was reached maintaining some stationbell in continuous operation. By using circuit-closers in normally open relation and providing them with a restoring spring by which the instant the hand of the operator is removed the normal status of affairs will be re-established, annoyances due to negligence on the part of an operator are safely and simply obviated. So long as the telephone is in use the call-bell is out of circuit. In lieu of a call-bell of course any other suitable indicator or aununciator might be employed.

What I claim as my inventionisl. A telephone system comprising a plurality of stations, individual line wires corresponding thereto, a plurality ot spring-impelled circuit @losers at each station connecting with the several individual wires corre spending to the other stations of the system and in normally open relation to an electric generator, and a telephone at each station individual wire and the other through a `bell or annunciator to a common return, and a normally short-circuited telephone inloperat` tive relationytothe latter branch `andlpermanently 'connected thereto.

3. A telephone system comprising al plul,

rality of stations, a plurality of individualliiie wires correspondingthereto, an electric generator at eaohstation having oneterniinal permanentl y connectedwitl two normallyclosed branches, one connecting Witnits `individual wire and the other with al common returr thro ugh its call-bell and "telephone, andmeans for establishinga normal short-circuitaround the telephone, and openingsaid'shortLcirciiit when the telephone is in serviceyth'e` other pole ot' the station generator being connected with one set of contacts ofl a series of normally open'circuit-closers, the other contacts of which are connectedwith the' individual lines corresponding to the-distant stations.`

4. A telephone system comprising-la* plurality of stations, an individualline wire for each station, aseries of normally open'circuitclosersat each station connectingwitli'the in`- dividual wires of other stationsa`generator at each station having one pole connected with the circuit`-closers, and the otherpole permanently connected with t'wo branches, one leading'to the individual wire of the station, and the otherthrough the `station telephone and annunciator to a common return;

5. A telephone system comprisingia plurality of stations, an individualline wirefer each station, a series of normally open circuit-closets at each station" connectingwitli the individual wires of the other stations, a generator adapted to be put into circuit with any of the individual wires, a telephone at In testimony whereof I have herento subscribed rny name this 19th day of June, A. D.

' FRANK R. OOLVIN.

Witnesses:

' E. C. GRIGG,

R. J. SIMEs, Jr. 

